Ferrous alloy



Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE 2,174,282 muonsALLOY James P. Gill, Latrobe,

Pa., assignmto Vanadium-Alloys Steel Company, Latrobe, Pa a corporationof Pennsylvania N Drawing. Original application February 21,

1939, Serial No. 257,686. Divided and this application March 30, 1939,Serial No. 264,983

1 Claim.

This invention relates to alloy steels and more particularly to alloysteels which are especially suitable for use in the manufacture of toolsor dies, and the present application is a division of my col-pendingapplication Serial No. 257,686,

filed February 21, 1939.

At present there are a number of steels of this nature in use but as arule, in order to make them conform to the general requirements of ready1!) forgeability and machinability, they are not sufficiently hard toofier a high resistance to abrasion. With this in mind, an importantobject of the present invention resides in the provision of an improvedalloy steel of this character which can be hardened to a Rockwellhardness in excess of C 60, whereby it offers a high resistance toabrasion, and yet can be readily forged and annealed so as to becommercially machinable.

A feature of the invention which contributes to the accomplishment ofthe recited object consists in the discovery that by the employment ofvanadium in a predetermined ratio in steels of the type under discussionit is possible to employ a carbon content far in excess of that employedin steels of this type that are in use at the present time. Thus, it hasbeen found that the element vanadium, because of its extremely highaffinity for carbon, will form carbides in the alloy, large amounts ofwhich will not go into solid solution at the normal hardening andforging temperatures. Even in the hardened state the improved steel willhave a comparatively tough matrix in which are embedded extremely hardcarbides.

In my Patent No. 2,105,115, granted January 11, 1938, the fact wasdisclosed that carbon contents up to 1.25% or 1.50% could be employed inmolybdenum steels as long as there was also present a vanadium contentin excess of two and one-half to one and below three and one-half to oneof the carbon content. This was an important discovery, but to repeat,it did not offer the wear resistance which forms the subject matter ofthe present invention. What I have now discovered is that steels havingcarbon contents in excess of 1.25% and less than about 3.50% carbon maybe prepared as long as the steel contains a vanadium content ofapproximately three times the amount of carbon present. Accordingly, inan alloy steel of the character under discussion having a. carboncontent in excess of about 1.25% and less than about 3.50% the vanadiumcontent would range from about 3.00% to about 11.00%.

To repeat, steels containing about 2.50% carbon or more have notheretofore been regarded as commercially forgeable, and an importantfeature of the present invention resides in the discovery, and theattendant disclosure, that such steels may be rendered readily forgeableby incorporating in them approximately three times as much vanadium ascarbon present. Steels so prepared have extremely high resistance towear, can be hardened extremely hard, some of them even as high asRockwell C '70, yet they can be annealed to a hardness of under 2'75Brinell, at which hardness they are commercially machinable.

In establishing the premises of my invention several series of heats ofsteel were prepared, some of which will be described in the ensuingparagraphs.

Heat No. 1

A steel was made containing 1.95% carbon, 1.20% silicon, 35% manganese,and 5.12% vanadium, which, by quenching in water from 1750 F'., produceda hardness of Rockwell C 69, and by quenching from temperatures as highas 2200 F. obtained a hardness as high as Rockwell C 67. This steel wasalso annealed to a hardness of 255 Brinell, at which hardness it couldbe readily machined. The steel was readily forgeable and forged withabout the same case as would a 1.00% carbon tool steel.

Heat No. 2

A heat of steel was prepared containing 3.05% carbon, 1.01% silicon,.32% manganese, and 9.60% vanadium, which it was possible to harden toapproximately Rockwell C '70 from 1600 F. and to Rockwell C 67 from 2200F. This steel was annealed to a hardness of 255 Brinell, at whichhardness it could be readily machined. It likewise forged with the sameease as a carbon tool steel of about 1.00% carbon content.

Having made the discovery that when the vanadium-carbon ratio wasapproximately that as given that such a material could be readily forgedand annealed and hardened to extremely h gh hardnesses, other alloyswere then added to the base composition given, namely, a carbon contentof from about 1.25% to about 3.50% and a vanadium content of from about3.00% to about 11.00%.

Heat No. 3

A heat of steel was made containing 3.10% carbon and 8.60% vanadium, towhich was added a tungsten content of 4.92%, and the material remainedforgeable.

Heat No. 4

This heat of steel contained a carbon content of 2.94% and a vanadiumcontent of 9.50%, to which was added 10.6% of tungsten. The materialremained forgeable and was found to reside within the premises of theinvention herein disclosed.

Two additional heats of steel were made containing 3.12% carbon and10.10% vanadium, and 3.14 33 carbon and 10.10% vanadium, to which wererespectively added 15.58% tungsten and 24.50% tungsten, but neither ofthese steels appeared to be commercially forgeable. It was thereforeconcluded that with the carbon on the higher side of the carbon rangeabout 12.00% tungsten was the maximum that should be added in order tomaintain the material commercially forgeable. In order to determine theupper limit of molybdenum, heats were prepared constantly increasing theamount of molybdenum present and it was found that the material was notcommercially forgeable in the higher carbon range after the molybdenumcontent exceeded about 10.00%. Molybdenum and tungsten were added todetermine the upper combined limit of both of these elements and it wasfound that as long as the combined amount of the two was under about10.00% the material could be successfully forged, whereas if thecombined amount exceeded this figure the material appeared to be nolonger commercially forgeable.

Ingots were made of the base composition already described containingboth tungsten and chromium, and also containing tungsten, molybdenum andchromium. With the chromium content as high as 5.00% and with the carboncontent approximately 2.00% it was found that either tungsten ormolybdenum, or both. could be added to a total percentage ofapproximately 12.00% and the material would still be commerciallyforgeable. It was found, however, that an ingot of 3.25% carbon, 8.90%vanadium, 10.79% tungsten, and 4.12% chromium formed with considerablediificulty, which would indicate that in the presence of about 10.00% oftungsten or molybdenum, or a total of both, that a chromium contenthigher than 5.00% could not be added and still obtain a commerciallyforgeable material. All of these compositions naturally contain varyingamounts of silicon, generally less than 1.50%, and a manganese contentgenerally less than .'75%, and additionally they also contain thecustomary small amounts of impurities of sulphur and phosphorus.

The purpose of adding other alloying ingreclients to the basecomposition was to alter the physical properties of the alloy so thatthe ma-- terial would have red hardness or would retain its hardness upto temperatures of approximately 1100 F. Hardened material made of thebase composition decreased slightly in hardness with an increase intempering temperature, but the material containing tungsten andmolybdenum, or both, with a chromium content of from 3.00% to 5.00% didnot materially decrease in hardness when the quenched specimens weretempered as high as 1100* F.

Ingots were made similar to those to which tungsten, molybdenum andchromium were added, but with a lesser vanadium content; that is, withthe vanadium content below 2.00%, and none of the ingots so made couldbe successfully forged, which is indicative of the fact that it is thepresence of the carbon-vanadium ratio that permits the material to beforgeable.

The following table will additionally serve to give informationconcerning a number of compositions which were prepared and isindicative of the manner in which the material forged:

Heat 0 Si Mn W Mo Cr Va Remarks 1136 3. 05 1. m .32 9. 00 Readilyforgooblc. 1137." 1.95 1.20 .35. 5.12 Do.

1138 3.10 .82 4.92 u... 8.00 Forgcablc.

1140... 2.10 1.31 .31 4. 72 5. 30 Readily forgcablc. 114]... 2.09 1.41.29 10.47 5.12 D0.

1144. 3.12 72 15. 58 10.10 Not iorucahlc. 1145... 3.14 .90 .35 24.501010 Do.

1147. 2. [)0 .00 .37 10.02 5. 05 Readily forgeahlc. 1148.. 1.99 .89 .382'3. 87 5. 05 Not foraeablc. 1150 1. 99 .00 .40 10. 47 4. 66 6. 00Forgeablc.

1lfil 2.06 .83 .27 5.20 3.93 1.93 6.30 Do.

The following table shows the Brlneli hardness that was obtained afterannealing some of these materials at a temperature of 1650 F.:

Heat number Fracture Quenching temperature, F. grain Sim DegreesFahrenheit Heat number asses Material made from heat 1161 afterquenching from 2350 F. retained a hardness of 68 Rockwell C aftertempering for one hour at 1050 F., definite proof of the red hardness ofsome of the compositions to which tungsten or molybdenum, or both, andchromium were added.

Material made from heat 1136 within the range of the basic compositionwhen quenched from 1600 F. and tempered at 1050" F. for 1% hoursCERTIFICATE OF Patent No. 2,l7l ,282.

JAMES P.

showed a hardness of 47 Rockwell C and when quenched from 2200 F. andtempered at 1050 F. for 1 hours showed a hardness of 57 Rockwell C,which indicates that while the material had some red hard propertiesthere was a noticeable drop in hardness when it was tempered at 1050 F.It was also found that material of the basic composition shows aresistance to abrasion of as much as 10 to 1 over that of carbon toolsteel containing 1.00% carbon and hardened to a Rockwell hardness of C67.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

An improved forgeable and machinable alloy steel, said steel containingfrom about 1.25% to about 3.50% carbon and from about 3.00% to not morethan 10% vanadium; the ratio of the vanadium to the carbon being inexcess of about 2 to 1 and less than about 4 to 1, with the re- 20mainder of the alloy substantially all iron.

JAMES P. GILL.

CORRECTION.

September 26, 1959.

GILL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 1h, for "10.6%" read 10.61%; and that the saidLetters Patent shouldbe read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1939.

(Seal) Henry Van Arsdale,

Acting Commissioner of Patents.

Degrees Fahrenheit Heat number asses Material made from heat 1161 afterquenching from 2350 F. retained a hardness of 68 Rockwell C aftertempering for one hour at 1050 F., definite proof of the red hardness ofsome of the compositions to which tungsten or molybdenum, or both, andchromium were added.

Material made from heat 1136 within the range of the basic compositionwhen quenched from 1600 F. and tempered at 1050" F. for 1% hoursCERTIFICATE OF Patent No. 2,l7l ,282.

JAMES P.

showed a hardness of 47 Rockwell C and when quenched from 2200 F. andtempered at 1050 F. for 1 hours showed a hardness of 57 Rockwell C,which indicates that while the material had some red hard propertiesthere was a noticeable drop in hardness when it was tempered at 1050 F.It was also found that material of the basic composition shows aresistance to abrasion of as much as 10 to 1 over that of carbon toolsteel containing 1.00% carbon and hardened to a Rockwell hardness of C67.

Having thus described the invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

An improved forgeable and machinable alloy steel, said steel containingfrom about 1.25% to about 3.50% carbon and from about 3.00% to not morethan 10% vanadium; the ratio of the vanadium to the carbon being inexcess of about 2 to 1 and less than about 4 to 1, with the re- 20mainder of the alloy substantially all iron.

JAMES P. GILL.

CORRECTION.

September 26, 1959.

GILL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 1h, for "10.6%" read 10.61%; and that the saidLetters Patent shouldbe read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November, A. D. 1939.

(Seal) Henry Van Arsdale,

Acting Commissioner of Patents.

